311 



Synopsis of the genera. 



1) The colony with luncecia: 



2) The colonies which have the form of a low cone or an arched 

 disc only show a single layer of zocEcia, whilst their inner cavity is 

 occupied by numerous avicularia placed in horizontal layers; (ooecia 



may occur) Conescharellina d'Orb. 



2) The colonies are plate-like or fan-shaped, with two layers of 

 zooecia;. (ocecia are not found) Bipora Whitelegge. 



1) The colonies, which have no luncecia, are plate-like, two-layered; 

 (no ooecia) Flabellipora d'Orb. 



Conescharellina angulopora Tenison -Woods. 



Bipora angulopora Whitelegge, Annals Nat. Hist. 6 Ser., Vol I, 1888, p. 18. 



(PI. XXm, figs. 7 a-7 f). 



The primary aperture is elongated oval, distally rounded, proximally pointed 

 and here provided with two elongated, rounded, triangular hinge-teeth, which 

 bound a narrow, elongated sinus. The peristome is formed by two thick cal- 

 careous plates, distally separated and projecting straight outwards, which have a 

 fairly strongly arched outer surface and reach almost to the proximal third of 

 the aperture. 



The operculum, which is extremely thick and of a brownish yellow colour, 

 is strongly arched in the greater part of its inner surface while the outer surface 

 has a corresponding concavity. The inner arched part which shows two small 

 muscular dots and evenly grades into a lower marginal portion ends proximally 

 in a narrow, tongue-shaped part, inserted in between the two hinge-teeth. Each 

 zooecium is separated from the adjacent zooecia by four long, narrow separating 

 walls and from one of the above-mentioned, small, enclosed avicularian chambers 

 by a small, innermost wall. Each of the four separating walls is provided within 

 each lateral margin with a row of up to 8 small, uniporous rosette-plates. 



The avicularia, appear in two different forms, those placed on the zooecia and 

 those occupying partly the flat base and partly a great inner portion of the 

 conical colony. The latter we may call the basal avicularia. The former which 

 occur in similar numbers to the zooecia and the frontal area of which has a 

 similar length as the zooecial aperture, are provided with a broad, triangular 

 mandible with its point directed as a rule obliquely distally towards the higher- 

 placed zooecial aperture in a neighbouring row and obliquely out from the surface 

 of the colony. The strong transverse bar between the opercular and the suboper- 



